"...after impacting the lunar surface, 0.1 to 1 percent of solar wind ions lose some energy and are reflected and scattered; solar wind ions normally contain helium nuclei and protons (hydrogen nuclei), but the solar wind ions that are reflected and scattered from the lunar surface contain no helium nuclei and are almost entirely made up of protons; and the reflected solar wind ions from the lunar surface are accelerated. Regarding lunar magnetic fields, many subtle magnetic nomalies have been confirmed near the South Pole on the farside. KAGUYA (in) a lower orbit observed the magnetic fields in more detail. Magnetic anomalies on the Moon are thought to have begun three to four billion years ago. By investigating plasma around the Moon and its magnetic fields, KAGUYA aims to explain the evolution of the Moon's magnetic environment."